Hipoxia modulates the secretion of growth factors of human umbilical cord-derived mesenchymal stem cells.

Background: Mesenchymal stem cell (MSC) has great potential as therapies due its ability to regenerate tissue damage and promote tissue homeostasis. Preconditioning of MSC in low oxygen concentration has been shown to affect the therapeutic potential of these cells. This study aimed to compare the characteristic and secretion of trophic factors of MSCs cultured under hypoxia and normoxia. Methods: MSCs were isolated from Wharton's jelly of human umbilical cord (UC) tissue by explant method and characterized by flow cytometry. Following 24 h of CoCl2-induced hypoxic culture, the viability and metabolic activity of MSC were analyzed by trypan blue exclusion test and methyl thiazolyl tetrazolium (MTT) assay, respectively. The secretion of hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) was assessed in conditioned medium using enzyme-linked immunosorbent assay (ELISA) method. Results: Flow cytometry analysis showed >99% of the population of MSCs cells were positive for CD73 and CD90 and > 62% were positive for CD105. While the cell viability of MSC was not affected by hypoxic cultured condition, the metabolic activity rate of these cells was decreased under hypoxic conditioning. In line with reduced metabolic activity, hypoxic human UC-derived MSC produced less HGF than normoxic counterpart. Compared to normoxic MSC, hypoxic preconditioned MSC secreted higher level of VEGF in the conditioned medium (p < 0.05). Conclusions: Hypoxia decreased the metabolic activity of MSCs associated with the modulation of HGF and VEGF secretions. It is suggested that hypoxia may also affect the therapeutic capacity of MSC cells.

Safety and efficacy of intraarticular hip injection using anatomic landmarks.

This study tests the hypotheses that the hip can be injected safely and reliably, using anatomic landmarks, without fluoroscopic guidance. Fifteen human cadavers (30 hips) were injected, each receiving one anterior hip injection and one lateral hip injection with methylene blue dye. Anatomic dissections were done on all 30 specimens to determine the rate of success and the proximity of the needle to the neurovascular structures about the hip with each approach. Neither the anterior nor the lateral injection approach, using published techniques based on anatomic landmarks, was sufficiently reliable to recommend for clinical use without radiographic guidance; the anterior approach was successful in only 60% of injections, and the lateral technique was successful in 80% of injections. In addition, the anterior approach, which is recommended in more reference works than any other approach, resulted in significantly more risk to the femoral nerve than did the lateral approach. The needle pierced or contacted the femoral nerve in 27% of anterior injections and was within 5 mm of the femoral nerve in 60% of anterior attempts. The anterior injection approach also resulted in needle placements significantly closer to the femoral artery and the lateral femoral cutaneous nerve than did the lateral approach. Using the lateral approach, the needle was never within 25 mm of any neurovascular structure in any injection. Some form of radiographic or sonographic guidance is recommended for needle placement during hip injections and aspirations; the lateral approach for needle placement seems safer than the anterior approach, with respect to the possibility of neurovascular injury.

Inpatient management of lower extremity amputations.

The in-hospital care of the amputee is crucial; careful preoperative, intraoperative, and postoperative regimens set the stage for a successful clinical outcome. Caring for the patient undergoing amputation is much more than choosing the correct level at which to cut. Early aggressive rehabilitation; careful attention to postoperative complications; and appropriate physical therapy, occupational therapy, and counseling all play pivotal roles. Thorough knowledge of these issues helps to increase the likelihood of a successful outcome and to keep morbidity to a minimum.

Primary repair of intraoperative disruption of the medical collateral ligament during total knee arthroplasty.

BACKGROUND: Intraoperative disruption of the medial collateral ligament during total knee arthroplasty is an uncommon complication that is frequently treated by implanting a prosthesis with varus-valgus constraint. To our knowledge, no data have been published on primary repair or reattachment of the medial collateral ligament and implantation of a minimally constrained posterior-stabilized or cruciate-retaining prosthesis. This retrospective study evaluates the hypothesis that satisfactory clinical results, at a minimum of two years, can be achieved with immediate repair or reattachment of the medial collateral ligament and without a constrained total knee prosthesis. METHODS: Of 600 knees treated with primary total knee arthroplasty, sixteen (in fourteen patients) sustained either a midsubstance disruption of the medial collateral ligament or an avulsion of the ligament from bone during the procedure. Preoperatively, all patients had either neutral or varus alignment and an intact medial collateral ligament. Midsubstance tears were treated with direct primary repair, and avulsions of the ligament off the tibia or femur were treated with suture-anchor reattachment to bone. All patients wore a hinged knee brace, with no limit to the range of motion, for six weeks postoperatively. Clinical and radiographic data were gathered prospectively as part of a database that was ongoing throughout the period of study; the cohort of patients was assembled retrospectively by searching that database. RESULTS: No patients were lost to follow-up. The mean duration of follow-up was forty-five months (range, twenty-four to ninety-five months). The Hospital for Special Surgery knee scores increased from a mean of 47 points (poor) preoperatively to a mean of 93 points (excellent) at the time of final follow-up. On physical examination, no patient had a Hospital for Special Surgery score in the fair or poor range and all patients had regained normal stability in the coronal plane both at full extension and at 30 degrees of flexion. No patient required knee-bracing beyond the initial six-week postoperative period. The range of motion at the time of final follow-up averaged 108 degrees (range, 85 degrees to 125 degrees ), although one knee required manipulation under anesthesia to obtain a satisfactory range of motion. No arthroplasties required revision. Radiographic examination demonstrated appropriate limb alignment in all patients at the time of final follow-up. CONCLUSIONS: Intraoperative disruption of the medial collateral ligament can be treated with primary repair or reattachment of the ligament to bone and postoperative bracing with good results; this avoids the potential disadvantages associated with the use of varus-valgus constrained implants.

Serum titanium level for diagnosis of a failed, metal-backed patellar component.

A case is presented in which an elevated serum titanium level was used to make the diagnosis of a failed metal-backed patellar component. The preoperative serum titanium level was 536.8 ppb, which was 98 times higher than the patient's previous level (taken 1 year earlier, when he was asymptomatic) and 2 orders of magnitude higher than the expected level with a well-functioning implant of this type. Revision surgery confirmed that the polyethylene portion of the patellar component had worn through, leaving the titanium portion of the patellar implant to articulate with the femoral component. Wear-through was not evident on preoperative radiographs or clinical examination. As knowledge about the expected ranges for serum metal ion levels after total joint arthroplasty continues to increase, the diagnostic utility of serum metal ion testing in the evaluation of joint arthroplasty function will continue to improve.

CT-generated 3-dimensional models for complex acetabular reconstruction.

Before undergoing complex acetabular reconstruction, 10 patients who met prospectively established criteria for severe acetabular bone deficiency received plain radiographs, computed tomography (CT) scans, and CT-generated 3-dimensional pelvic models. The radiographs, CT scans, and models each were graded according to the American Academy of Orthopaedic Surgery (AAOS) classification for acetabular deficiency. The classifications for the radiographs, CT scans, and models were then compared with findings at surgery. The models predicted acetabular deformity and AAOS classification significantly better than the other imaging modalities. The models agreed with the surgical findings in 9 of 10 cases, compared with 2 of 10 for the CT scans (P = .016) and 4 of 10 for the plain radiographs (P = .063). The models closely predicted the available space for the hemispheric acetabular shells, based on the size of the last reamer used, for the 6 hips reconstructed with standard components. Four patients required custom acetabular components; in 2 of those 4, the need for custom components was not anticipated by plain radiographs or CT scans. Three-dimensional CT-generated acetabular models were found to be useful in preoperative planning of complex acetabular reconstructions.

The effect of joint loading on acetabular wear measurement in total hip arthroplasty.

All radiographic calculations of acetabular wear assume concentric reduction of the prosthetic articulation. To date, no studies have shown that the femoral head is fully reduced on standard radiographs, and we have seen cases on early postoperative radiographs in which this assumption is not met. Using our computerized radiographic technique, 78 paired anteroposterior pelvic radiographs in 46 patients at a mean of 14 months after surgery (range, 1-92 months) were evaluated with and without joint loading. Displacement with loading was analyzed against time since surgery, a surrogate for acetabular wear. Regression analysis found a statistically significant increase in femoral head displacement after loading with longer duration of follow-up, but the rate of this increase was small (0.027 mm/y). This difference affects calculated wear values by <15%. We conclude that in a low-wear cohort, joint loading does not affect radiographic calculations of acetabular polyethylene wear in a clinically important way.

Cancellous allograft in revision total hip arthroplasty. A clinical review.

There are numerous indications for the use of cancellous allograft bone in the context of revision hip arthroplasty. These indications range from the well-documented use of morselized bone chips to fill cavitary defects during cementless acetabular reconstructions--in which complete or near-complete graft remodeling is expected--to the use of particulate allografting with bipolar hemiarthroplasty for acetabular revision, which largely has been abandoned because of frequent component migration, graft resorption, and clinical failure. Most other indications, including femoral and acetabular impaction allografting techniques, curettage of osteolytic defects with component retention, and complex reconstructions using acetabular reconstruction rings or cages with cancellous donor bone, are controversial but are supported by published clinical series. The current study reviews the literature on cancellous allografting in revision total hip arthroplasty.

Extended hindfoot fusions and pantalar fusions. History, biomechanics, and clinical results.

Contemporary techniques of hindfoot and ankle arthrodesis can result in a high rate of osseous union, pain relief, and patient satisfaction. Methods range from open approaches to fully arthroscopic surgical techniques. Arthrodesis should be limited to the joints involved with the arthritic, deforming, or neuromuscular process because the rate and severity of progressive adjacent joint degeneration appear related to the number of joints fused initially. Appropriate joint position, maintained with stable internal fixation applied in compression and augmented with bone-graft material when necessary, should be considered the gold standard for most hindfoot and ankle arthrodeses. External fixation may be used in the revision or salvage setting if needed or when soft tissues or bone stock do not permit stable internal fixation. Meticulous attention must be given to the handling of soft and hard tissues as well as to correction of the underlying deformity and to appropriate positioning of the joints in question. Newer techniques, such as intramedullary fixation, arthroscopic or arthroscopically assisted ankle arthrodesis, and total ankle arthroplasty, have shown some promise and warrant more extensive study.

Effect of cryopreservation and oviductal cell conditioned media on Ca2+ flux of equine spermatozoa.

Movement of Ca2+ into spermatozoa is a critically important event for capacitation and the acrosome reaction. In the present study, the nature of Ca2+ movement in fresh equine spermatozoa was established and the effects of oviductal cell conditioned medium (OCM) and cryopreservation on Ca2+ flux were investigated. The ability of fresh and cryopreserved stallion spermatozoa to regulate Ca2+ concentration over time was evaluated in Ca2+ -free PBS. Intracellular Ca2+ concentrations were higher in cryopreserved spermatozoa than in fresh spermatozoa. However, extracellular Ca2+ concentrations were higher in fresh spermatozoa than in cryopreserved spermatozoa. Both fresh and cryopreserved spermatozoa took in 1 mmol exogenous Ca2 l(-1) immediately and rapidly, reaching a plateau in <5 min. The rate of Ca2+ internalization did not differ between fresh and cryopreserved spermatozoa. Oviductal epithelial cells from non-pregnant mares were incubated in TCM-199 and the OCM was harvested after 48 h to evaluate the effect of the OCM on sperm Ca2+ flux. Spermatozoa were incubated in either OCM or TCM-199 for 1 h before microscopic evaluation and Ca2+ concentration determination in PBS. Cryopreserved spermatozoa had higher intracellular and lower extracellular Ca2+ concentrations than did fresh spermatozoa, but incorporated Ca2+ at a slower rate than fresh spermatozoa. OCM incubation increased the relative intracellular Ca2+ concentration in fresh but not cryopreserved spermatozoa compared with spermatozoa incubated in TCM-199 (P < 0.01). In summary, oviductal cell products affect Ca2+ internalization by equine spermatozoa. Cryopreservation strongly affects all aspects of sperm Ca2+ control, regardless of other factors. These results indicate that the high intracellular Ca2+ concentrations of cryopreserved stallion spermatozoa may be one of the reasons why mares must be inseminated very close to ovulation to maximize pregnancy rates using cryopreserved semen.

Cementless acetabular revision. Evaluation at an average of 10.5 years.

This study reviews the clinical and radiographic results of 138 consecutive cementless acetabular revisions in 131 patients performed for aseptic loosening at a mean of 10.5 years followup. Kaplan-Meier survivorship of these components was 84% at 11.5 years. Two components (1.8%) in two patients were considered aseptically loose based on radiographic criteria; one patient was symptomatic but the component was not revised because of the patient's poor health, and the other patient was asymptomatic. Pelvic osteolysis was present in 19 hips (17%), appearing at a mean of 103 months. All but two of these were small lesions (< 2 cm) at the periphery of the components. Nevertheless, the incidence of osteolysis has increased with time, and continued followup is warranted. Separation or fragmentation of the fiber-metal porous pads was uncommon (8.3%), but was significantly associated with pelvic osteolysis; this finding has not been reported before with this component. Five patients underwent late revision surgery (after 100 months), one for deep infection, one for periprosthetic femur fracture, and three for late recurrent dislocation. Harris hip scores averaged 81 points (good) at final followup, which is unchanged from the authors' last report on this group. Acetabular revision with a fiber-metal hemispherical component appears durable at a mean followup of more than 10 years.

High rate of failure of allograft reconstruction of the extensor mechanism after total knee arthroplasty.

BACKGROUND: Disruption of the extensor mechanism is an uncommon but devastating complication of total knee arthroplasty. Several techniques for reconstruction of the extensor mechanism after total knee arthroplasty have been reported, but we do not know of any study in which the results of one group's method were corroborated by a second group using the same technique. In the present series, we evaluated the results of reconstruction of the extensor mechanism with use of allograft according to the method described by Emerson et al. METHODS: Seven reconstructions of the extensor mechanism with use of a bone-tendon-bone allograft were performed with the technique of Emerson et al. in six patients. The patients were evaluated before and after the operation. The knee score according to the system of The Hospital for Special Surgery, evidence of an extensor lag, use of walking aids, and the ambulatory status of each patient were recorded. The patients were also asked about, and the medical records were reviewed for, episodes of falling related to weakness of the quadriceps after the reconstruction. The mean duration of follow-up was thirty-nine months (range, six to 115 months). As these reconstructions often fail early, the minimum duration of follow-up was six months. RESULTS: All seven reconstructions were rated as clinical failures on the basis of a persistent or recurrent extensor lag of more than 30 degrees. All but one patient needed an assistive device full time for walking, and four patients (five knees) had at least one documented episode of falling that was due to giving-way of the affected knee. Four of the reconstructions were revised; one revision was performed with use of another extensor mechanism allograft and three were performed with use of a medial gastrocnemius rotation flap. The other three clinical failures had not been revised at the time of writing. At the time of the most recent follow-up (or at the time of revision of the extensor reconstruction), the mean extensor lag was 59 degrees and the mean knee score was 52 points (a poor result). CONCLUSIONS: Undertensioning of the allograft reconstruction at the time of the operation and attenuation of the allograft both may have played a role in the inability of the patients to regain active extension of the knee postoperatively. Alternative techniques for reconstruction of the extensor mechanism or modifications of this technique should be considered in the treatment of this difficult problem.

Impaction allografting with cement for revision of the femoral component. A minimum four-year follow-up study with use of a precoated femoral stem.

BACKGROUND: Cancellous impaction allografting with cement for revision of the femoral component has conventionally been performed with a polished, tapered implant, which was designed to allow subsidence of the component. However, subsidence has been associated with pain in the thigh, dislocation of the hip, and revision of the component. This prospective study tested the hypothesis that good clinical results can be achieved--without subsidence of the component--with use of impaction allografting and a precoated, collared, straight stem for difficult femoral revisions. METHODS: Twenty-nine patients had revision of the femoral component with use of impaction allografting with cement and a Harris Precoat stem. Impaction allografting was performed when loss of metaphyseal and diaphyseal bone precluded revision with more straightforward techniques or when reconstitution of bone was considered a specific goal of the reconstruction (as was sometimes the case with revision of the component in younger patients). The patients were followed prospectively and were evaluated with use of the Harris hip score and serial radiographs. The patients were followed for a minimum of four years (mean, sixty-three months), except for four who died. RESULTS: Four patients died before the minimum four-year follow-up period had elapsed; all four had the prosthesis in place at the time of death. The Harris hip scores improved from a preoperative mean of 54 points (poor) (range, 21 to 91 points) to a mean of 87 points (good) (range, 41 to 100 points) at the time of the most recent follow-up. Kaplan-Meier survivorship analysis, with aseptic loosening as the end point, was 92 percent (95 percent confidence interval, 82 to 100 percent) at six years; one additional hip failed because of a hematogenous infection at seventy-three months postoperatively, for an overall failure rate of 12 percent (three of twenty-five patients) at the time of the most recent follow-up. Two hips needed a repeat revision; one was revised because of subsidence of the stem with recurrent osteolysis and the other, in a patient who had hemodialysis, because of late sepsis. A third femoral component subsided and failed but was not revised. Radiographic evidence of bone-stock reconstitution was observed in six (29 percent) of the twenty-one patients for whom radiographs were available. As in other series of patients managed with impaction allografting, the complication rate was high; excluding the revisions, three reoperations were performed, and six patients had either intraoperative femoral fracture or perforation necessitating cerclage wiring or cortical strut allografting and cerclage wiring at the time of the procedure. There were six nonunions in eighteen patients who had been operated on with a transtrochanteric approach. CONCLUSIONS: Difficult revisions of the femoral component with use of impaction allografting and a precoated stem provided satisfactory clinical and radiographic results at the time of intermediate-term follow-up. However, the high rate of complications in our series led us to refine our indications for the procedure.

Diminished material properties and altered bone structure in rat femora during pregnancy.

Pregnancy and lactation are known to cause structural and mechanical changes in bone, but the effects of pregnancy alone have not been evaluated thoroughly. This study used radiographic measurements, torsion testing, mineral analyses, and histological evaluation to determine whether there are changes in bone material and geometric properties during pregnancy in the growing rat, as implied by earlier biochemical and histological studies. The bones of pregnant 9 to 12-week-old rats and controls that were not pregnant and were matched by age (but not weight) were evaluated at times corresponding to 5, 10, 15, and 20 days of the 23-day gestation period to address the following questions: (a) How is the growth of whole bone affected by pregnancy in the growing rat (as determined by radiographic analyses)? (b) How are the mechanical properties (structural and material) of whole bone affected by pregnancy (as assessed by torsion testing)? (c) Are there changes in the characteristics of bone mineral during pregnancy (as determined by measurement of mineral content and x-ray diffraction analyses)? and (d) Are there detectable morphological or ultrastructural differences between the bones of pregnant and control rats (as assessed by analyses based on histology and back-scattered electron imaging)? The presence of statistically significant differences in this study was determined initially on the basis of a two-factor analysis of variance. In general, significant differences were noted only at late gestation (day 20), when the bones were longer and had a greater outer radius and cortical thickness; this indicates that more growth occurred during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

False-positive diagnosis in fine-needle aspiration of an atypical Warthin's tumor: histochemical differential stains for cytodiagnosis.

Cytologic smears of a Warthin's tumor (WT) typically consist of sheets of oncocytic (oxyphilic) cells and scattered lymphocytes. Reparative foci within this neoplasm can occur, which may give rise to exfoliated, malignant-appearing, squamous-like cells. A false-positive diagnosis of squamous carcinoma can occur when these atypical cells dominate the cytologic aspirate. Histochemical and immunoperoxidase stains may aid in diagnosing an atypical WT when the usual cytologic features are absent.